There is known a film forming apparatus using the so-called ALD (Atomic Layer Deposition) method as a method of forming a thin film such as a silicon nitride film on a substrate (hereinafter, referred to as “wafer”) such as a semiconductor wafer. The apparatus using such an ALD method has a configuration in which a plurality of wafers mounted on a rotary table in a vacuum container is rotated with the rotation of the rotary table such that the wafers pass sequentially through a region to which a raw material gas is supplied and a region to which a reaction gas reacting with the raw material gas is supplied. In this apparatus, the raw material gas is supplied from a gas nozzle which extends in a diameter direction of the rotary table and has gas discharge holes formed along a length direction thereof. The gas nozzle needs to be installed parallel to the wafer so as to adsorb the raw material gas with high in-plane uniformity and to increase in-plane uniformity of a film forming process.
As an inclination adjustment mechanism which adjusts an inclination of the gas nozzle in this kind of substrate processing apparatus, there is known a structure in which the inclination of the gas nozzle with respect to a horizontal axis is controlled by adjusting a height level of a support member for supporting the gas nozzle from below and fastening the support member to a sidewall of a vacuum container by an inclination adjustment screw. In the inclination adjustment mechanism, the gas nozzle is inserted into the support member where the gas nozzle is subjected to a minute height adjustment by inclination adjustment screws which are disposed at two positions in a right-left direction. This complicates the adjustment operation.
In addition, to increase precision of the height adjustment requires finely working a screw thread. To meet such a requirement, the support member and the inclination adjustment screw are constructed by metal, and surfaces thereof are coated with a corrosion-resistance film. However, it is likely that, when tightening the screw, the film is peeled off, thus generating unwanted particles. As such, a technique is required to easily regulate the height of the support position of the gas nozzle with a simple configuration.